From: Samuel Just <sjust@redhat.com>
Date: Mon, 25 Oct 2021 06:26:05 +0000 (+0000)
Subject: crimson/os/seastore/.../lba_btree: fix lower_bound at_boundary()
X-Git-Tag: v17.1.0~607^2~1
X-Git-Url: http://git.apps.os.sepia.ceph.com/?a=commitdiff_plain;h=542d237ffef70b60f851320ac7432c331859d47e;p=ceph-ci.git

crimson/os/seastore/.../lba_btree: fix lower_bound at_boundary()

Clarify that lookup_depth_range may return an iterator at_boundary() and
audity users.

Fix LBABtree::lookup to correctly handle at_boundary() after the call to
lookup_depth_range.

Fixes: https://tracker.ceph.com/issues/52805
Signed-off-by: Samuel Just <sjust@redhat.com>
---

diff --git a/src/crimson/os/seastore/lba_manager/btree/lba_btree.cc b/src/crimson/os/seastore/lba_manager/btree/lba_btree.cc
index ba166fb127a..3190d59d48b 100644
--- a/src/crimson/os/seastore/lba_manager/btree/lba_btree.cc
+++ b/src/crimson/os/seastore/lba_manager/btree/lba_btree.cc
@@ -44,6 +44,7 @@ LBABtree::iterator::handle_boundary_ret LBABtree::iterator::handle_boundary(
 	}
 	leaf.reset();
 	get_internal(depth_with_space).pos++;
+	// note, cannot result in at_boundary() by construction
 	return lookup_depth_range(
 	  c, *this, depth_with_space - 1, 0, li, ll, visitor
 	);
@@ -113,9 +114,11 @@ LBABtree::iterator_fut LBABtree::iterator::prev(op_context_t c) const
       }
       ret.leaf.reset();
       ret.get_internal(depth_with_space).pos--;
+      // note, cannot result in at_boundary() by construction
       return lookup_depth_range(
 	c, ret, depth_with_space - 1, 0, li, ll, nullptr
       ).si_then([&ret] {
+	assert(!ret.at_boundary());
 	return std::move(ret);
       });
     });
diff --git a/src/crimson/os/seastore/lba_manager/btree/lba_btree.h b/src/crimson/os/seastore/lba_manager/btree/lba_btree.h
index 10ec1a6b04c..dedf8e239e4 100644
--- a/src/crimson/os/seastore/lba_manager/btree/lba_btree.h
+++ b/src/crimson/os/seastore/lba_manager/btree/lba_btree.h
@@ -494,6 +494,14 @@ private:
     });
   }
 
+  /**
+   * lookup_depth_range
+   *
+   * Performs node lookups on depths [from, to) using li and ll to
+   * specific target at each level.  Note, may leave the iterator
+   * at_boundary(), call handle_boundary() prior to returning out
+   * lf LBABtree.
+   */
   using lookup_depth_range_iertr = base_iertr;
   using lookup_depth_range_ret = lookup_depth_range_iertr::future<>;
   template <typename LI, typename LL>
@@ -579,7 +587,14 @@ private:
 	    0,
 	    li,
 	    ll,
-	    visitor);
+	    visitor
+	  ).si_then([c, visitor, &iter] {
+	    if (iter.at_boundary()) {
+	      return iter.handle_boundary(c, visitor);
+	    } else {
+	      return lookup_iertr::now();
+	    }
+	  });
 	}).si_then([&iter] {
 	  return std::move(iter);
 	});